DE3415572A1 - OPTICAL RADAR DEVICE FOR A VEHICLE - Google Patents

Description

The invention relates to an optical radar device for vehicles for determining the distance from an obstacle according to the preamble of claim 1 and a method for determining said distance.

A conventional radar system for vehicles is published in JP-OS 55/86000. It is about a Radar device with electromagnetic waves. In the last However, time is an optical radar device with a laser search beam for vehicles has been proposed.

The optical radar device has a control unit, which generates and processes electrical signals. Furthermore, there is an optical transmitter, which the search beam in a predetermined Wavelength emits and an optical receiver is available that receives the light that is reflected by Objects, and which converts the collected light into a corresponding electrical signal.

The control unit has, inter alia, a pulse modulator 20 which sends a trigger signal to a signal processing unit gives away. The trigger signal is generated simultaneously with a pulse drive signal generated. The pulse drive signal excites the light emitting Element in the optical transmitter for emitting an associated light pulse. This is through a lens in focuses a beam sent from the front of the vehicle. Weak reflected light is focused through a large diameter lens, the focused light passes through an optical filter that

Niseaii Motor Co., Ltd.

Background light (for example, sunlight, comes from artificial Lighting, etc.). The filtered light occurs on the light-receiving surface of a light-sensitive Element, which is arranged in the focal point of the lens and is converted there into an associated electrical reflection signal, which consists of narrow pulses of low amplitude consists. The reflection signal is in a broadband amplifier the control unit - amplified and shaped = The amplified signal is passed on to a processing unit, which the transit time delay of the reflected light pulse in in relation to the light pulse emitted by the transmitter from the time delay between the trigger signal and the pulse signal determines from what it is possible to calculate the distance to the reflecting object in a known manner.

In the known radarsysteirj the from the optical transmitter The transmitted beam shows slight divergence to ensure that objects are detected relatively close in front of the vehicle can.

When the opening angle and the direction of the strarile are fixed, is the detection limit distance (the distance at which objects are not counted as obstacles, itself if detected) limited so that objects in adjacent lanes are not detected while the vehicle is in motion driving down a road. An object that lies outside the determined limit distance in front of the vehicle, cannot be determined.

When driving on a curved road, the beam is greatly offset from the vehicle's lane so that a vehicle ahead cannot be detected. The deviation of the ray from the curved track

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increases as the radius of curvature of the road decreases.

The invention has for its object to provide an optical radar device with increased investigative limiting distance, di ^ objects not erraittelt in adjacent tracks. The invention is also based on the object of specifying a method that works with an increased detection limit distance.

The invention is related to the device c ?. ; .rch the Features of claim 1 and, with regard to the method, given by the features of claim 21. Beneficial Refinements are the subject of subclaims.

The device according to the invention differs from the known optical radar device described above by having a Suehst-rahlschwenkeinrichtung has, which moves the search beam back and forth parallel across the road surface. The distance to be reflective Objects, in turn, are measured from the transit time difference between a transmitted and a received pulse.

With the device according to the invention and with the according to the invention With this method, it is also possible to reliably determine vehicles driving ahead even on a curved road.

The invention is explained in more detail below with reference to figures explained. Show it:

Fig. 1 is a block diagram of a conventional optical

Radar equipment for vehicles;

Niss.ari Motor Co., Ltd.

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Pig. Figure 2 is a timing diagram of the main signals of the Pig device. I;

3 shows a diagram over the determination area of a conventional facility in a straight road;

FIG. H shows a diagram according to FIG. 2, but for a curved road; FIG.

5 shows a block diagram of a radar device according to the application;

6 shows a more detailed block diagram of the device according to FIG. 5J

Fig. 7 is a timing diagram of the most important waveforms the device of Fig. 6;

FIG. 8 shows a cross section through the transmitting and receiving part of the radar device from FIG. 6; FIG.

Fig. 9 is a cross section through the main part of the transmitter;

Fig. 10 is the circuit diagram of the pulse drive circuit of the transmitter according to FIG. 9;

11 is a perspective schematic illustration

a deflecting mirror and mirror rotating device of the device of Fig. 6;

Nissan Motor Co., Ltd

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FIG. 12 is a perspective schematic view of FIG Components of the mirror drive;

13 is a perspective view of the device of Figure 6 mounted on a vehicle;

14 is a diagram showing the relationship between

an electrical current supplied to the mirror drive and the angle of rotation of the deflecting mirror;

15 shows a diagram of changes in direction of the |

Search beam caused by the deflecting mirror;

FIG. 16 is a block diagram of the range determiner of FIG Circuit of Fig. 6;

FIG. 17 is a flow chart as received from the microcomputer of FIG Device according to Figure 6 is carried out;

Fig. 18 shows a deflecting mirror driving circuit;

19 shows a diagram of a circuit connected to the circuit according to FIG. given signal;

Fig. 20 is a diagram of the function of the device when

the vehicle turns a curve; and FIG. 21 is a diagram of the facility when the vehicle

drives along a straight road.

To lead to the subject matter of the invention is first

on the basis of Fig. 1 a conventional optical radar device

p tion described. This has a control unit X which |

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generates and processes electrical signals. An optical transmitter Y sends a search beam with a predetermined wavelength the end. An optical receiver Z collects light reflected from objects and converts the light into a corresponding one electrical signal around.

A pulse modulator 1 sends a trigger signal b to a signal processing unit 3. The trigger pulses b are emitted simultaneously with driver pulses a for the transmitter. The driving pulses have a period Tp (approximately 100 µs), a pulse width Tw (approximately 50 ns), and a peak value Vo, as shown in FIG. Excited by a driver pulse, a light-emitting element 2 of the optical transmitter Y emits a light pulse Lt of a wavelength \ and a pulse width Tw. The light pulse Lt is focused by a lens 4 into a beam with an opening angle Ot. Weak light Lr reflected by objects within the path of the search beam is focused in the receiver Z by a lens 5 of large diameter. The reflected light Lr collected by the lens 5 passes through an optical filter 6 that filters out background light (e.g. sunlight, artificial light, etc.) and then strikes the light-receiving surface of a photosensitive element J which is at the focal point of the lens 5 is arranged. There the light is converted into an associated electrical reflection signal c with narrow, weak pulses. The reflection signal c is amplified and shaped by a broadband amplifier into a strong signal D, which is then fed to the signal processing unit 3, which determines the delay time f of the reflected light pulse Lr compared to the pulse Lt emitted by the transmitter Y from the temporal relationship between the trigger signal b and to the

· Nissasi Motor Co., Ltd, W8 ^ 2 ^ 1ß7 (3} / H

Pulse signal d, from which the distance R to the reflected light can be calculated as follows:

R = c * r / 2

where the units of R and f are meters and seconds, respectively

and c is approximately 3 χ 10 m / sec.

In the radar system described, the beam Lt emitted by the optical transmitter Y has an aperture angle of approximately 70 mrad. Its optical axis g is at right angles to the front of the vehicle J _1, as shown in FIG. 3, in order to ensure that objects relatively close in front of the vehicle J can be detected.

If the opening angle Qt and the direction of the light beam Lt are fixed, a detection limit distance r «(over which objects are not regarded as obstacles even if they are detected) is limited when the vehicle is traveling along a straight road, as shown in FIG 3 is shown. Assuming that a lane of an average road has a width V / of about 5 m and it is assumed that the distance spanned by the ray Lt to each side of the lane corresponds to the detection limit distance r i, r _Q ^ W / Q _fc = 70 m, so that objects that are 100 m or more in front of the vehicle cannot be determined.

When the vehicle J drives around a curve, as shown in FIG. 1, the beam Lt falls out of the lane, so that a preceding vehicle Jf cannot be detected can. The deviation of the ray Lt from the curve increases as the radius of curvature Ra of the curve decreases.

Motor Co., Ltd.

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. The notifying proper device according to FIG 5 comprises an optical transmitter 11 ^r to see that a search beam substantially j |. sends out parallel to the road surface. An optical em- | Receiver 12 receives light reflected from objects, one | Control unit 10 determines the distance to the reflecting | renal objects due to the temporal relationship between the emitted light beam and the received light. Its scanning device SU sees the axis of the search beam repeatedly back and forth so that the light beam repeatedly travels through a scanning field. j

The control unit 10 has, as in Pig. 6, an I clock generator 13, a wide-band amplifier 14, a decision a Mikrokompueer 16, a D / A \ ι fernungsbestimmer 15, ι converter 17 and a deflection driver 18. The microcomputer 16 receives a signal S5 from a steering angle sensor 19 which indicates the respective steering angle of the steering wheel. Like in Pig. 7, the clock generator 13 generates a trigger signal S1 with a period Tp (~ 0.1 ms) and a pulse width Tt (~ 100 ns), which is fed to the optical transmitter 11. In response to the trigger signal Sl, this generates a search beam pulse Lt of a wavelength Λ, a pulse width Tw (^ 50 ns) and a repetition period Tp.

The part Lr of the search beam Lt reflected by an object (not shown) is received by an optical receiver 12 detected, which emits an electrical reception signal S2, which is transmitted by the broadband amplifier 14 '' strengthens and is shaped and then the distance determiner 15

corresponds to the distance to an object and depends on

the delay time Z of the received signal S2 relative to the _{

Trigger signal Sl is calculated. The distance signal · S4 |

is fed to the microcomputer 16. i

Nissan Motor Co., Ltd.

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Fig. 8 is a cross section through the transmitter 11 and the receiver 12 parallel to the road surface. The housing the transmitter 11 and the receiver 12 are combined in one unit. The receiver 12 has a convex lens 121 with a large diameter which collects light Lr reflected from the object. An optical filter 122 filters out background light such as sunlight or artificial light. It can be an interference band filter, with a center wavelength Λ. A photoelectric converter 123,

z. B. a PIN photodiode with a relatively large light-receiving surface (e.g. 7-10 now diameter) receives the light Lr reflected by the filter 122. A preamplifier 124 with a bandwidth of a few tens of MHz and a gain of 20 - 30 dB amplifies the signal from transducer 123 and outputs through a coaxial connector · 125 a signal S2 from.

The transmitter 11 has an optical transmission unit 111, a Deflection mirror 116, which swivels the optical signal Lt from the transmitting unit 111 back and forth parallel to the surface, and a mirror rotary drive 117. As shown in Fig. 9, The transmission unit 111 comprises a pulse driver 114 and a laser diode 113 in a hollow cylindrical housing, and a convex lens 112 inserted into an opening of the housing is appropriate. As shown in FIG. 10, the pulse driver 114 is constructed so that when the Trigger signal Sl from the clock generator 13 is given to him via a Kcaxial plug 114, a transistor Ql to Conductivity triggers and thereby a charge (of about 150 V), which in one with the collector of the transistor Ql connected capacitor Cl is stored, to a laser diode 113, which is between the emitter of the transistor Ql and earth is connected.

Nissan MQtor Co., Ltd.

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The search beam Lt transmitted by the transmitting unit 111 is along a predetermined path; through a reflection mirror 118 deflected, which is arranged directly in front of the convex lens. The deflected beam occurs on a deflecting mirror 116 and is emitted through a window 119 at the front of the vehicle.

The deflecting mirror 116 is mounted on an axis 32 of a rotating mirror drive 117 (FIG. 11). The axis rotates by a predetermined angle corresponding to an electric current Id, which is fed to the mirror rotary drive 117 through the deflection driver 18, whereby the mirror 116 is rotated.The deflection angle θ of the search beam Lt, caused by rotating the mirror 116 corresponds to twice the rotation angle Q _{2 of} the mirror 116, that is

θ = 2Θ _2. .. (ϊ)

Fig. 12 shows the basic structure of the mirror rotary drive 117, the two opposing each other Permanent magnets 30 (south pole) and 3I (north pole) and one having rotatably mounted electromagnet 33 with a winding Ci between the two permanent magnets on the axis 32 passing through its center. The deflecting mirror 116 is at the top of the Axle 32 attached and at its lower end this is with a spring 35 connected to the housing.

The coil Ci is controlled by the deflection driver 18, a D / A converter I7 and the microcomputer 16 via slip rings 36 and 37 a current Id is fed to the top and bottom of the axis 32, which excites the rotatably mounted electromagnet 33, which leads to a force F with the direction indicated by arrows in FIG. The magnet 33 is twisted

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together with the axis 32 until the opposing force of the Spring 35 corresponds to the twisting magnetic force.

Fig. 13 shows the arrangement of the transmitter 11, the receiver 12 and the control unit 10 on a vehicle and the way egg smell Lt is sent.

The mirror drive II7 rotates the mirror 116 at an angle θ «which corresponds to the current Id. The relationship between the current Id and the angle θρ is shown in FIG. J.4 shown. The current Id changes triangularly with a period 2T- and an amplitude 21p, so that the mirror swings back and forth _{repeatedly with a period 2T Q.}

If the scanning range (swivel _{width) of the search strable Lt is Q t} and the center angle of the scanning field is V- (the angle between the center line of the scanning field and the optical axis g of the transmitter 11), the relationship between the current Id and the rotation angle Q applies _? the following equation:

Id = Iv- + 21p (^ i- - 2n) .... (2)

where 2n ^ ~ ^ 2n + 1 and I v ~ is a constant current. Id = Xf + 21p (2 (n + 1) - ± - I .... (5)

where 2n + l = "- | - ^ 2 (n + l)
0

α - Σ j. _9 / JL 0 ^ ¹ X / ji \

"2" 2 '2 ^V T _O * ■ "2' ^ /

where 2n ^ ~ - ^ 2n + 1
¹ O

whereby

Nissan Motor Co., Ltd.

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where η = 0, 1, 2, 3, ...., I / * "is ^a constant current and t is the time.

The direction of the search beam Lt thus changes as shown in FIG. The following relationship then applies to the relationship between the angle 9, which is present between the search beam Lt and the optical axis g, and the pivot angle 0 _fc:

Q = where Q = where

<ä _t (~ - in -

2n ^ ~ - ^ 2n + 1 ¹ O

(6)

f2 (n + 1) - I -! -

l ^ -J- ^ 2 (n + 1). ¹ O

The center angle y- v; is set in accordance with the steering angle of the vehicle, which changes when the vehicle turns a curve. The angle Y- is monitored by the microcomputer 16 which controls the scanning of the search beam Lt and carries out various control processes based on the range values S4 from the range finder I5, as will be described below.

As shown in Fig. 16, the range finder 15 an RS flip-flop 151, which is triggered by the trigger signal Sl is set by the clock generator 13 and by the signal S3 is reset by the broadband amplifier 14. A High frequency generator 152 generates a high frequency Pulse train which is fed through an AND element 153 to a high-speed counter 154 which counts the pulses of the pulse train.

Nissan Motor Co., Ltd. , ·· .. ". * 'WC83256 / d87 O ) / SH

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The AND gate 15J5 is opened by the output signal from the RS flip-flop 151 during the time delay between the trigger signal S1 and the received signal SJ, so that the pulses reach the counter 15I only during this time. This accordingly outputs a count value that corresponds to the time delay. The count is given to the microcomputer 16 as a distance signal Sk. The steering sensor I9 determines the angle of rotation of the steering wheel. To do this, he has z. B. on a potentiometer which is connected to the steering wheel, and whose output signal is given to the microcomputer 16 as a binary coded signal S5.

The flow chart of the operation of the microcomputer 16 FIG. 17 has essentially three main procedures. A scan control controls the deflection of the Search-5 Beam Lt depending on the radius of a curve through which the vehicle is traveling, i.e. H. based on the steering angle data from the steering angle sensor I9 to determine objects in front of the vehicle in the curved part of the road. A discovery limit distance control controls the determination limit angle for both sides of the lane, so not objects can be determined in adjacent lanes. A distance differentiation distinguishes whether objects are within the detection area lie outside a safety distance, and thus whether there is a risk of collision.

In the specified scanning control method, the value S5 is read in a step S1, which corresponds to the steering angle θ des

The steering wheel corresponds to how it is output by the steering angle sensor 19. In a step 2, the center angle of the scanning angle Q. of the light beam Lt is calculated on the basis of the angle. The microcomputer 16 outputs a control signal S6 which determines the center angle of the search beam Lt

Maiior Co., Ltd.

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a.uf K "sets, via the D / A converter 17 to the deflection driver 18; whereby the rotating mirror 116 to a corresponding Angle is twisted.

The calculation of the central angle Y- for calculating a voltage signal Ea is described below. As shown in FIG. 20, the center angle χ indicates the angle between the center axis i of the scanning angle 9,. of the search beam Lt and the optical axis g of the transmitter. Changing the center angle V - depending on the determined steering angle of the vehicle makes it possible to determine objects in front of the vehicle, even in curves. The center angle V ~ is set so that the radially inner extreme value of the search beam Lt (set when the deflection angle 0 assumes its inner extreme value) is tangential to the radially inner edge Ii of the lane. If the angle which extends between an axis h which lies at right angles to a segment OQ, which connects the center Q of the front of the vehicle J and the midpoint of the curve 0, and the tangent to the track edge Ii, with oL. is designated, the center angle V- can be described by the following equations:

where A is the actual steering angle, ie the angle between the axis H of the front wheels and the longitudinal axis of the vehicle, ie the optical axis g. This actual steering angle / 3 is given as follows according to Ackerman's development theory:

= Lh / Ra

• · ■. (9)

.. .. Nissan Motor Co., Ltd,

415572

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where Ra is the radius of curvature of the curve and Lh is the lane width of the vehicle. The actual steering angle ρ can therefore also be expressed as follows:

'~ k

(10)

where k is a constant and Q ^ is the actual steering angle as measured by sensor 19. Δ is proportional to the steering angle 0_ of the steering wheel.

The values of OL and β of equation (8) cannot be measured directly, so that the center angle Y- must be calculated from other known data, which will be briefly explained below.

Assume that the vehicle J is traveling along the center of a W-width lane. Since the angle oC corresponds to the angle in the middle of the curvature 0 of the track between the front center Q of the vehicle J and the axial point R. of the search beam, the following applies:

cos c < = ORb / OQ = Ra / (ra + - |

Since Ra is very large compared to V /, we have in equation (11)

Ra / (Ra + %) h 1 - (W / 2Ra)

Since u ζ 1, we have Cos ot = 1 - fo / 2)

and therefore σ (_ = yW / Ra

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Substituting equations (9) and (12) into equation (8) it follows:

._ Lh, W_ _ ^ t

For the radius Ra in formula (13) follows from the equations (9) and (10)

Ra fc Lh / k / Gsj
Substituting Ra into equation (13) it follows:

- / k-0 _s -W / Lh - (e _fc / 2) (15)

If the steering angle © s of the steering wheel is known, the center angle V ~ can be calculated.

The deflection driver 18, which has an operational amplifier OP, changes the current Id through the winding Ci around the rotatable magnet 33 of the mirror rotating driver 117 as a function of changes in the voltage signal Ea which are supplied to it, as shown in FIG. The voltage signal Ea is a triangular wave of a period 2T _n , an amplitude Ep and a lower voltage level Er (Fig. 19). In this embodiment, the value of the period 2T _Q is chosen such that T_ = 512 Tp, so that during the time T _Q 512 false of the search beam Lt is sent. The amplitude Ep of the voltage signal Ea and the lower voltage level He have the following relationship and are in

Λ <* »t» XY / -7 \ Y / U \ J TT »-Y__ Λ_ 1 * · Π TT» J Tf »1

ociJi'X l / l> cn \ JJ uiiu \ T / vico JTiUWjJiCUiCO gcmau rig. * f uc—

calculates:

Ep = Ip-Ri = K'0 _fc / 2 (16)

Er = Ir-Ri = K-r - Ep (17)

.flissan Mptor Co., Ltd WJ03236 / l € | i5) /

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where 9. the scanning angle of O ^ JO mrad of the search beam Lt, Ri is the input resistance of the operational amplifier OP of the deflection driver 18 and K is a constant which is calculated from the properties of the magnetic rotary drive 117.

The calculation of the voltage Ea is carried out in steps (5), (6) and (7) the flow chart performed as a function of the elapsed time to apply the voltage signal Ea to the triangular shape to be adjusted according to FIG. The following applies:

Ea = Er + 2Ep & 2n)

¹ O

where 2n ^ -ψ- ^ 2n + 1 0

Ea = Er + 2Ep i2 (n + 1) t

(18)

where 2n +

<2 (n + I)

In this way, the voltage signal Ea (FIG. 19) is given to the deflection driver 18, whereby the mirror 116 is rotated back and forth repeatedly (step (8)).

Then, the determination limit distance rc is calculated to facilitate the determination of objects outside the lane impede. This is done on the basis of the deflection angle θ of the search beam Lt. In a step (9) (FIG. 17) the deflection angle θ from the voltage Ea obtained in steps (6) or (7) based on the following formula (20) calculated derived from equations (16) and (17)

θ = 2Θ ₂ = Ea / k

, Nissan Ijfetpr Co., Ltd

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After the signal S4 that the distance R to the determined Object indicated by the range finder I5 in one Step (10) is indicated, the size of the steering angle is ös checked in a step (11). If J9s | ^ 0.05, then inferred from this that the vehicle is traveling on a straight road, while if the result is NO, a curve is closed on drive durelti.

If it is concluded in step (11) to drive straight ahead, the program goes to a step (12) in which the Determination limit distance rc is determined by the following formula (21):

rc = W / 2

(21)

That is, when the vehicle J is traveling on the center line of a straight road as shown in FIG. 21, the determination limit distance rc is the distance to the point P in which the search beam Lt, which is at a deflection angle θ is sent, the lane boundary intersects Ii. When the width of the track is W, the limit distance rc is through Equation (21) is given.

On the other hand, when it is determined that the vehicle is turning, the routine goes to a step (IJ above, in which the determination limit distance rc is determined depending on the calculations described above *

When the vehicle is cornering, the distraction

in the following area:

- V ² - ^g - f ⁺ V ²

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ο / λ ι- c η ->'.' · i ■ ·. ·: ': ^ 30 ^ / 3.37 (3) / sh

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where ue-r search beam Lt scans an area Q to the angle.

If a point at which a search beam Lt transmitted under the deflection angle θ crosses the outer curved track line ^ of the lane is denoted by P, and the point at which a lirle, which extends from P at right angles to the segment OQ, the Segment OQ, which intersects, is designated as H, the following equations apply:

Segment QH = rc-sin (G - / *) (23)

Segment PH = rc-cos (ö - / S) ...

Since the length of the segment is OQ = Ra + W / 2, it follows from the equation (23):

Segment OH = segment OQ - segment QH

= (Ra + W / 2) - rc-sin (0 - / i) (25)

From the Pythagorean theorem in the triangle OHP it follows:

(Segment PH) ² i- (Segment OH) ²

= Segment PO) ² (26)

where segment PO = Ra + W (27)

Substituting equations (2k), (25) and (27) into equation (26) it follows:

² co5 ² (G ß ) + (^ Ra + W / 2 rcsin (G / Vj ²

rc ² .co5 ² (G - ß ) + (^ Ra + W / 2 - rc-sin (G - / j

= (Ra + W) ² .... (28)

Nissan Motor Co., Ltd. '"'. ',' · '..'."'.; ^w p832 ^ 6 ^ 1 _t 87 (3) / SH

From the formulas (22), (8) and (l6) it follows:

θ - h έ / ■ - P) + Q. / 2 = ei = / W / Ra (29)

For example, if the radius of curvature of the curve is Ra s 1,000 m and the width of the track W - 4 m 1st, gives equation (29):

θ - ft ^ 0.06 «1 (30)

\ Hence: V

cos ² (β - / S ) = 1 - (0 - fh ) ² (31) j

sin (9 - f] ) = 9 - f) (32) I.

Substituting equations (3I) and (32) into equation (28) gives the
following equation:

rc = (ra + - ^) (θ - / 5)

(28) the determination limit distance rc results from the ]

By an approximation method for equation (33) and Umord- | The result is that rc 2: 0 f

rc = {(0 - Λ) + -γ / (θ - Λ) ² + W / Ra j Ra (34)

Since the radius of curvature Sa is an unknown numerical value, the detection limit distance rc can then be calculated are eliminated when Ra is eliminated using equation (18) from which the distance as a function of the steering angle 0 s results according to the following equation:

rc = £ (θ - />) + γ (θ - f> Γ + ^ Srjirli - · Ο5) Calculating the limit distance rc according to equation (35) leads

«♦ Il

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* t i

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Nissan Motor Co., Ltd,

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to reliable determination of objects in a curved track without being influenced by other objects in adjacent tracks * The prevention of paying attention of objects outside of the lane is actually performed in a step (I ² O, in which the distance R is checked to the object ahead of the vehicle to see if it is less than the value derived from equations (21) or (35) If R is greater than rc, it is concluded that the object is out of the lane and the distance values are not taken into account and the program ends immediately.

When an object is detected in the lane, the likelihood of a collision becomes dependent on the Distance to the object determined. This is done in one step

(15) compared the distance R to the object with the braking distance Rs, which is determined depending on the respective vehicle speed. When the distance R to the object is less than the braking distance Rs, there is a high possibility of a collision, so that in a step (16) an output signal for generating an alarm is given.

The braking distance Rs is the distance that the vehicle covers before it comes to a standstill after the driver has noticed the object and then brakes as hard as possible. The braking distance is based on a signal from a speed sensor (not shown) having a different routine (not shown) based on the following Calculated equation:

Rs = Va-Td + Va / 2 σι

• - · (36)

Nissan Motor Co., Ltd Wc! 33236 / i87O) / SH

where Va. the driving speed, ^ - the deceleration and Id is a delay time.

The method described makes it possible, regardless of whether the vehicle is on a straight or curved road Road drives to reliably determine whether an object is in the lane and, if so, in which one Distance, whereby an optical radar device of high reliability is achieved.

The connection of the exemplary radar device Having an automatic trip control enables more precise follower control, which leads to behind a preceding vehicle can be driven with a suitable distance between them.

The distance R to the object and the direction to the object, which is determined on the basis of the deflection angle 0 of the search beam Lt when determining the distance R, are known, which further improves the effectiveness.

As stated in detail above, the optical radar device according to the application and the method according to the application are provided sure that objects in a lane can also be reliably detected in curves. The investigation limit distance is increased without objects outside the track to be examined being detected. This is an optical radar device high effectiveness achieved.

Claims (6)

TER MEER-MULLER STEINMEISTER PATENT LAWYERS - EiUROPEiAIM PATENT ATTORNEYS DipL-Chem. Dr. N. ter Meer Dipl.-Ing- H. Steinmeister S £ ⁿ a ⁹ sse ζ ^MÜVter Artur-Ladebeok-Strasse 51 D-8OOO MUNICH 22 D-4S00 BIELEFELD 1 Mü / J / ho / b April 26, 1984 NISSAN MOTOR COMPANY, LTD. 2, Takara-cho, Kanagawa-ku, Yokohama, shi, Kanagawa-ken, Japan Optical radar device for a vehicle Priority: May 6, 1985, Japan No. 58-79141 (P) EXPECTATIONS Optical radar device for a vehicle with - An optical transmitter (11) for sending a search beam to possible objects on a street who drives the vehicle, - An optical receiver (12) for receiving light from the search beam that is reflected from the objects is and - a determination device (10) for determining the distance of the vehicle from the objects on the basis the temporal relationship between the emitted and the received light, . "..". ".: Nisserj Motor Co., Ltd. characterized by - a scanning device (116, 117) for repeated Scanning with the search beam parallel across the street. 2. Device according to claim 1, characterized by a sensor (19) for determining the Lenkv? Iii ± cbls of the vehicle and for outputting a steering angle signal, which indicates the size of the steering angle, wherein the scanning device (116, 117) the orientation of the search beam relative to an optical axis of the transmitter (11) in accordance with the steering angle signal specifies. 3. Device according to claim 2, characterized in that the scanning device has an alignment device (116) for aligning the search beam on an object, with an axis (32) about which the rest of the dressing device rotates in order to set the direction of the search beam, and that the scanning device has an adjusting device for moving the aligning device as a function of the steering angle signal. 4. Device according to claim 3 »characterized in that the aligning device ^ is a mirror (II6) and the adjusting device has a device (30, 3I) ^for generating a magnetic field and an electromagnet (33) which is in the HagueITeId a.ugec> i ^- diieL iöü and TeöL with the AchöS (32) of the mirror is connected so that the electromagnet rotates depending on the steering angle signal when Nissanjfotor Co., Ltd. it is fed to a corresponding electrical signal to the steering angle f * ^r current, thereby DER mirror and f. the search beam is twisted. |, 5. Device according to claim 4, characterized in that | indicates that the axis (32) is | extends through the electromagnet (33) and has a pair of slip rings (36, 37) attached to the Axis of the mirror (116) each for a connection of the electromagnet, so that current through the- same can flow. μ 6. Device according to claim 5> marked I by a hang-on device (35) for | Stopping the electromagnet (33) in a position corresponding to the strength f of the current. f 7- device according to one of claims 4-6, da- | characterized in that the 1 felol generating device a pair of permanent magnet ; te (30, 31) which are antiparallel from one another are spaced apart, and that the Elektromag- ί net (33) is arranged in the space so that it | is freely pivotable. | 8. Device according to one of claims 4-7, ge | identified by a | second mirror (118) arranged to face Jf the search beam on the. first mirror (II6) directs, | before it deflects the search beam back. 1 • Nissan Motor Co., Ltd. If ·· m • f · 9. Device according to one of claims 2-8, characterized by a control device (16), which determines whether there are objects within a limit distance in front of the vehicle, and which determines whether the distances to the objects are greater than the braking distance over which the vehicle is traveling moves before it comes to a stop at full braking when the distances to the objects are less than the detection limit distance. 10. Device according to claim 9> characterized by a warning device for dispensing an alarm if the distance to the objects is less than the braking distance. 11. The device according to claim 9 or claim 10, characterized in that the d Detection limit distance is a function of steering angle 12. Device according to one of claims 9-11, characterized in that the Discovery limit distance is a function of road width. 13 · Device according to one of Claims 9 to 12, characterized in that the Detection limit distance is a function of the pivot angle. 14. Device according to one of claims 4 - I3, characterized in that the Electromagnet (33) an operational amplifier (OP) ... Nissaji .Motor Co., Ltd. with a negative and a positive input, one Resistor (Ri) connected to the negative input to supply power to the op amp, whose positive input is grounded, and has a coil winding (Ci) connected to the negative input and is connected to the output of the operational amplifier. 15. Device according to one of claims 2-14, characterized in that the Control device (16) based on the orientation of the search beam relative to the optical axis of the transmitter of the steering angle signal is calculated and repeatedly outputs a deflection angle signal to the search beam pivot which deflection angle signal is a periodic triangular signal. 16. Device according to claim I5, characterized in that that the control device (ΙΟ) determines whether the vehicle is on a straight or drives on a winding road to determine a detection limit distance depending on the type of road, to determine whether the distances of objects are within this limit distance and to determine, whether these object distances lie within the braking distance within which the vehicle is under full braking comes to a standstill. 17. Device according to claim 16, characterized in that that when it is determined that the vehicle is traveling on a winding road, the limit distance roughly by the equation ., ".." ·. ".: Nis.se.n ^ Motor Co., Ltd. where 0 is the deflection angle of the beam, A is the angle between the optical axis of the transmitter (11) and the direction in which the front wheels roll, Lh is the wheelbase, W is the width of the road and Os is the longitudinal angle of the vehicle. 8. Device according to claim 16, characterized in that when it is determined that the vehicle is traveling on a straight road, the limit speed rc is given by W / 2 JQf , where W is the width of the road and / 0 j is the deflection angle of the Search beam is = 19. Device according to claim 16, characterized in that that the braking distance Ί5 through Va. Td + Va / 2K _{Q is} given, where Va is the vehicle speed, Td is the driver's startled time and (\ _{0 is} a vehicle-dependent deceleration factor. 20. Device according to claim 15, characterized in that - indicates that the control device (10) calculates a second angle between the scanning axis of the search beam and the optical axis of the transmitter (11) on the basis of the steering angle signal and also calculates an electrical signal, the eiru ax treme scanning position of the search beam on the basis of the second angle defines which electrical signal is a periodic triangle signal. "Nissan Motor Co., Ltd. V758L5236 / 18 () / 21. Method for determining the distance of objects on a Road on which a vehicle is traveling with the following steps: - sending a beam of light onto the objects, - Receiving light reflected from the objects and - Determining the distances of the objects from the vehicle on the basis of the temporal relationship between the transmitted search beam and received light, characterized in that the search beam transmitted periodically over the road surface scanned 22. The method according to claim 21, characterized in that the steering angle of the Vehicle is determined and the deflection angle of the search beam is determined on the basis of the determined steering angle will. The method of claim 22, characterized in that the step of determining of the deflection angle contains a step for determining an extreme scanning position of the search beam. 24. The method according to claim 23 * dad indicates that it is determined whether the vehicle is along a straight line or along a curved line Road drives that calculates a detection limit distance depending on the aforementioned step it is determined whether the distances from objects are less than the calculated limit distance, that it is determined whether the distances to the objects are less than a braking distance the vehicle during the time in which the driver recognizes the objects, brakes the vehicle to the maximum and comes to a standstill brings «